The skin of a Djinn Kin is tinted some unnatural color; green, blue, red, purple; so at least it’s easy to tell them apart from the rest of us. Their body temperature is also significantly higher than a proper human’s, such that it’s uncomfortable to touch one for very long. Not that any decent person would want to touch one anyway.
Djinn Kin have a d4 hit die, and they advance as Thief for experience gain and saving throws.
At first level, and each time a Djinn Kin levels up, they can make a single Wish. Their wishes must be phrased in the terms of the game world, without reference to mechanics or metagame materials. It is a desire put into words by their character, and should reflect that.
As with any wish, the referee should act in good faith. Discuss openly the outcome of the character’s wish. Be receptive to refinements of its phrasing, and suggestions for its potential effects. The referee always has the final word on when the discussion is over, and what the effects will be. However, a Wish should be a player’s blank check to make something awesome happen, not an excuse to fuck the player over.
Likewise, players should view a Wish as a blank check to make something awesome happen, not an opportunity to make themselves game-breakingly powerful. Infinite money, invincibility, more wishes, if those’re is the sort of things you wish for, you’re an asshole. Why not just wish to “win” D&D? All you’re doing is creating a situation where the referee has to figure out how to ‘beat’ you just so the game can continue.
Wish for a great big beard of iron twine that will protect you from oncoming attacks. Wish that every creature you encounter will view you as a member of its own race. Wish you could punch with the force of a battering ram. Wish that no blade could ever touch you. Wish to be able to see in every environment as though it were a brightly lit room. There’s a universe of cool possibilities.